Intel PCH (Haswell) Sound (ALSA) Problem and Fix for Arch Linux

The main problem fixed by the method explained here as follows: 

1. The kernel sound modules loaded just fine and able to recognize all sound-related chips just fine.
2. The Intel PCH platform (in my case Haswell) seems to be perfectly fine in loading modules. Moreover, checks via alsautils programs seems to work as well.
3. There's no sound coming out of the analog output. The analog output is usually the ones which a laptop speaker is connected and the one which you put earphone jack into. If you are using HDMI output from your Intel platform. You might not need this fix.

The "hint" that problem exists is usually failure when running:
$ speaker-test
with rather cryptic error message akin to "unable to open XXXX file"

This fix is focused on my Haswell Laptop but it could also work on other Intel systems with PCH as well. The basic idea comes from this post: https://bbs.archlinux.org/viewtopic.php?id=180102. The only different thing is details of the hardware. The basic idea of the fix is: to force ALSA to reorder the module loading so as to make the sound chip controlling the analog output becomes the default output.
This fix ensures that the sound coming out of the default sound device is coming out of the analog output instead of the HDMI output. Anyway, you should have a sort of hint on which PCI device in your machine that controls the analog audio output. Usually, in Intel PCH platform (at least in Haswell), the ones that controls the analog output doesn't connect to the CPU directly, but rather to the PCH because the CPU (i.e. the HDMI device in the CPU chip) only connects to HDMI output. You should consult the system block diagram to ensure about this.

The fix consists of a *.conf file in /etc/modprobe.d. This file instructs the kernel module loader, i.e. the ALSA subsystem to reorder the sound modules so as to make the PCH audio device the "default" one (having index 0). In my case, I name the *.conf file: /etc/modprobe.d/alsa-base.conf. This is the contents of my /etc/modprobe.d/alsa-base.conf:

# Intel PCH
options snd-hda-intel index=0  model=auto vid=8086 pid=9c20
# Intel HDMI 
options snd-hda-intel index=1  model=auto vid=8086 pid=0a0c

The meaning of the module configuration file above is to set PCI device with Vendor IDentifier (VID) 8086 and PID 9C20, i.e. Intel PCH  as the default sound device (with index value set 0). You can find your specific vid and pid with this following command:

$ lspci -nn | grep -i audio
00:03.0 Audio device [0403]: Intel Corporation Haswell-ULT HD Audio Controller [8086:0a0c] (rev 09)
00:1b.0 Audio device [0403]: Intel Corporation 8 Series HD Audio Controller [8086:9c20] (rev 04)

This is the output of aplay -l in my system after I applied the fix:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC3239 Analog [ALC3239 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

As you can see, the PCH audio device has become the "default" audio device (card 0). With the fix, speaker-test no longer stops with "unable to open XXXX file" but outputs noise sounds from the speaker. This is an excerpt of speaker-test log from my terminal:

$ speaker-test

speaker-test 1.0.28

Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 2048 to 16384
Period size range from 1024 to 1024
Using max buffer size 16384
Periods = 4
was set period_size = 1024
was set buffer_size = 16384
 0 - Front Left
Time per period = 2.657561
 0 - Front Left
Time per period = 2.986723
 0 - Front Left

I hope this also helps those experiencing similar problems out there. Ciao.

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